1. Field of the Invention
The present invention relates to an ultrasonic imaging apparatus wherein the scale setting is automatically performed.
2. Description of the Prior Art
A conventional ultrasonic imaging apparatus is known wherein one picture is displayed on a monitor screen as a still image (or "freeze display") by utilizing a video signal recording/reproducing unit such as a video tape recorder, and desired medical information, e.g., a cardiac beat period is obtained from the still image.
Generally, in an imaging apparatus for performing a freeze display of an ultrasonic image recorded in a video signal recording/reproducing unit, one picture of the ultrasonic image represented by a video signal is stored in a memory unit and the picture is displayed on a monitor so as to measure a caliper and an area thereof. During a diagnosis, a number of ultrasonic images are recorded in the video signal recording/reproducing unit, and are reproduced later for measurement.
In the conventional apparatus, in order to measure an ultrasonic image displayed on the monitor, scale information (scale factors and depths of a body) of the ultrasonic image to be measured is supplied to an image measurement circuit in the ultrasonic imaging apparatus through a panel switch or the like. This requires a cumbersome switching operation upon observation of the displayed ultrasonic image. Every time the scale factors of the ultrasonic image to be measured are changed, the cumbersome switching operation must be repeated, which is time-consuming and inconvenient for an operator. In addition, erroneous measurements may be made due to erroneous operation.
Particularly, in M mode operation, it is necessary to determine a depth of an object under examination and time lapse as scale factors. Therefore, the switching operation must be independently performed in accordance with the scale information of each ultrasonic image.
The present invention has as its object to provide an ultrasonic imaging apparatus wherein scale setting for an ultrasonic image displayed on a monitor can be automatically performed, so that a work load for an operator can be reduced, measurement time can be shortened and reliability of measurement results can be improved.